CURB-65: A Severity Assessment Tool for Community-Acquired Pneumonia
CURB-65 is primarily used to assess the severity of community-acquired pneumonia (CAP), predict mortality risk, and guide site-of-care decisions including hospital admission and ICU assessment. 1
Components and Scoring
CURB-65 evaluates five clinical parameters, with one point assigned for each:
- Confusion (mental status change) 1
- Urea >7 mmol/L (BUN >19 mg/dL) 1
- Respiratory rate ≥30 breaths/minute 1
- Blood pressure (systolic <90 mmHg or diastolic <60 mmHg) 1
- Age 65 years or older 1
Risk Stratification and Clinical Application
The CURB-65 score correlates with mortality risk and guides treatment decisions:
| Score | Mortality Risk | Recommended Management |
|---|---|---|
| 0-1 | 0.7-2.1% | Consider outpatient treatment [1] |
| 2 | 9.2% | Consider short hospital stay or supervised outpatient treatment [1] |
| 3 | 14.5% | Hospital admission, assess for ICU [1] |
| 4-5 | 40-57% | Hospital admission, assess for ICU [1] |
Advantages of CURB-65
- Simplicity: Uses only five variables compared to PSI's 20 variables, making it more practical in emergency settings 1, 2
- Accessibility: Requires only one laboratory test (urea/BUN), which is readily available in most hospitals 1
- Validated Performance: Effectively predicts mortality with an area under the curve of 0.77 3
- Efficient Resource Allocation: Helps reduce unnecessary hospitalizations while ensuring appropriate care for higher-risk patients 1
Simplified Version: CRB-65
- A variant that omits blood urea nitrogen testing (CRB-65) is available for settings where laboratory tests are not readily accessible 1, 2
- CRB-65 is particularly useful in outpatient settings and resource-limited environments 1
Limitations and Considerations
- CURB-65 may underestimate severity in young patients with severe respiratory failure and in elderly patients with comorbidities 1
- The sensitivity of CURB-65 (score ≥2) for predicting critical care interventions is approximately 78.4%, indicating some high-risk patients may be missed 3
- When used for ICU admission decisions, CURB-65 performs less effectively than criteria specifically designed for ICU triage, such as the IDSA/ATS severe CAP criteria 1, 2
- A significant number of patients with CURB-65 scores ≤2 may still require ICU admission and critical care interventions 3
Comparison with Other Scoring Systems
- The Pneumonia Severity Index (PSI) is more complex but similarly effective in predicting mortality 1, 4
- PSI is primarily designed to identify low-risk patients who can be safely treated as outpatients 4, 2
- Recent meta-analyses suggest CURB-65 may have slightly better performance in early mortality prediction and higher sensitivity (96.7%) and specificity (89.3%) for predicting ICU admission compared to PSI 5
Best Practices for Implementation
- Use CURB-65 as an adjunct to clinical judgment, not as the sole determinant for site-of-care decisions 1
- Consider implementing CURB-65 as part of a systematic approach to CAP severity assessment 1
- For patients with CURB-65 scores ≥3, promptly evaluate for potential ICU admission 1
- Exercise caution when using CURB-65 alone to guide disposition, as some patients with low scores may still require critical care interventions 3